Art of telephony signaling



March 21, 1933. c, A, MOKEE 1,901,919

ART OF TELEPHONY SIGNALING Filed June 21, 1929 5 i K H '3 f INVENTOR.(70/?062 4 Mfikee A TTORNE Y.

Patented Mar. 21, 1933 UNITED STATES PATENT OFFICE CLARENCE A. MCKEE, OFBRONX, NEW YORK, ASSIGNOB, BY MESNE ASSIGNMENTS, TO

WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A. CORPORA-TION OF NEW YORK ART OF TELEPHONY SIGNALING Application filed June 21,

This invention relates to signaling in telephony and more particularlyto call signals which are usually characterized by the employment of aso-called ringing circuit in which is included a bell or other audiblesignaling device signaling a call to a subscriber or station.

In many instances, it is found desirable to signal the subscriber orstation visually instead of audibly while in other cases both audibleand visual signals: are preferred. No satisfactory method or means toaccomplish this result has heretofore been suggested for use incommercial telephone systems, while in private intercommunicati ngsystems the only practical results thus far obtained are through thecase of independently energized local circuits acting through eitherautomatic or manual control devices. Relatively weak currents areemployed for the bell-ringing circuits and in order to produce a visualsignal such a circuit has been utilized to operate a relay in a localcircuit to complete the latter and thus energize a lamp includedtherein.

The use of local circuits to light lamps, as heretofore, is open to manypractical disadvantages. For example, ordinary commercial lightingcurrent is generally used and this, of course, necessitates the carefuland adequate insulation throughout the system with attendant expense. Inmany instances, moreover, current outlets are not convenient, and longleads through armored cable and conduit are required with incidentexpense and frequently unsightly installation.

/Vith the foregoing consideration-s in mind, the object of the presentinvention is to produce a visual signal in the ringing circuit withoutnecessitating the employment of relays or manually controlled devicesand without any other extraneous source of current supply.

The method of this invention consists, generally speaking, in passing analternating ringing current through both visual and audible signalingdevices or through a visual signal device alone, while precluding theflow of direct current through such devices 1929. Serial No. 372,586.

at all times. Another phase of the present i v Features of theinvention, other than those specified, will be apparent from thehereinafter detailed description and claim, when read in conjunctionwith the accompanying drawing.

In the accompanying drawing, I have illustrated different wiringdiagrams showing the manner in which the method of this invention may bepractically carried out, but the showing therein made is to beunderstood as illustrative, only, and not as de fining the limits of theinvention.

Figures 1, 2 and 3 show wiring diagrams illustrating difierent Ways ofpracticing this invention.

Referring to the drawing, 1 designates a bell ringing circuit and inwhich circuit is included the usual polarized bell or buzzer 2, and acondenser 3. The circuit as thus far described is a conventional bellringing circuit employing alternating current for the operation of thebell. The present invention may be associated with this: conventionalcircuit in various ways. For example, as shown in Figure 1, a circuit 4%may be connected into the circuit 1, so as to shunt the bell 2 and thecondenser 3 and in this circuit 4 is included a condenser 5 and a visualsignal 6.

In the showing of Fig. 2, the circuit 40 is connected into the circuit1, so as to merely shunt the bell 2. The circuit 4a; includes the visualsignal 6, but does not require a condenser corresponding to the.condenser 5.

In the showing of' Fig. 3, a circuit 4?; is connected into the circuit1, so as to shunt both the bell 2 and condenser 3 and said circuit 4?)includes a condenser 55 and the primary coil 7 of a step-up transformer.The secondary 8 of which transformer is included in a circuit 9 whichalso includes a visual signal 6. As a modified form of the constructionof Figure 3, the condenser 51) may be omitted and the circuit 4?)arranged so as to merely shunt the bell 2 after the manner illustratedin Fig. 2. Thus, the condenser 3 of the bell ringing circuit mayfunction in this circuit alone or may serve to function for both thecircuits 1 and 4a or 1 and 4b. The purpose of employing a condenser inseries with the visual signal is to preclude passage of direct currentthrough the visual signal and thus preclude normal short circuiting ofthe direct current circuits of the telephone system, irrespective of thekind of visual signaling device employed.

With the arrangements described in the several figures, the visualsignal is arranged, in effect, in multiple with the audible signal 2,and these signals are therefore operated simultaneously when the circuit1 is completed from the central oilice or through Switchboardconnection, or in any other suitable way known to the art for energizingbell ringing circuits.

In practice it is feasible to either mute the audible signal or to omitit from the ringing circuit although in most installations, it isdesirable to operate the two alarms simultaneously. Furthermore, thesetwo alarms may be positioned at widely separated places to be heard andobserved respectively by different persons. It is also within thepurview of this invention to include in the shunt circuits describedmore than one visual signal, this being preferably accomplished byconnecting such visual signals in the shunt circuit, for example thecircuit 4, in multiple.

I wish to call particular attention to the fact that the current forenergizing the visual signal is derived from the ringing circuit, i. e.,it is the ringing current. In practice, this current has heretoforegenerally been so weak, for reasons well understood in the art, that itwill not operate well known lamps used for signaling purposes intelephony generally. I have discovered, however, that even with a weakcurrent ordinarily used, it is entirely feasible to obtain thoroughlysatisfactory visual signalin through the employment of non-filamenttubes, such, for instance, as a neon tube. Tubes of this character arefound to operate with high efiiciency in a ringing circuit and thecurrent consumption thereof is practically negligible. Furthermore, theywill operate on a very weak alternating current, such as is generallyemployed in the bell ringing circuits of telephones.

It is, moreover, practical in some instances to utilize a neon tube inthe manner described without a condenser in series, but for certainother types of visual signaling devices which may be employed, thepresence of a condenser in series therewith is not only desirable butnecessary to preclude shorting. The economy of current consumption oftubes of the character described makes it possible to connect such atube in multiple relation with a polarized bell in a ringing circuitwithout appreciably affecting the operation of the bell under normalcurrent conditions.

I have specifically referred to neon tubes as illustrative of thepresent invention, but I wish it understood that I do not limit theinvention to this particular tube, as other suitable equivalent visualsignaling devices may be used for this purpose.

The foregoing detailed description sets forth the invention in itspreferred practical forms and defines the preferred manner of practisingthe invention, but said invention is to be understood as fullycommensurate with the appended claim.

Having thus fully described the invention, what I claim as new anddesire to secure by Letters Patent is:

In a telephone signaling system, the combination of an alternatingcurrent ringing circuit, a condenser and an audible signaling deviceincluded in series in said circuit, and a circuit connected to theringing circuit and shunting said condenser and audible signalingdevice, said shunt circuit including a condenser and a visual signalingdevice.

In testimony whereof I have signed the 1

